On Fri 12 Oct 2018 at 18:04, Marcin Wojtas <[email protected]> wrote: > > pt., 12 paź 2018 o 17:55 Ard Biesheuvel <[email protected]> > napisał(a): > > > > On 12 October 2018 at 07:06, Marcin Wojtas <[email protected]> wrote: > > > pt., 12 paź 2018 o 03:41 Wu, Hao A <[email protected]> napisał(a): > > >> > > >> > -----Original Message----- > > >> > From: Marcin Wojtas [mailto:[email protected]] > > >> > Sent: Thursday, October 11, 2018 11:43 PM > > >> > To: Wu, Hao A > > >> > Cc: Ni, Ruiyu; Ard Biesheuvel; Tian, Feng; Tomasz Michalec; Dong, > > >> > Eric; edk2- > > >> > devel-01; Gao, Liming; [email protected]; Kinney, Michael D; Zeng, > > >> > Star > > >> > Subject: Re: [edk2] [PATCH v2 2/4] MdeModulePkg/SdMmcPciHcDxe: Add > > >> > UhsSignaling to SdMmcOverride protocol > > >> > > > >> > wt., 9 paź 2018 o 13:51 Marcin Wojtas <[email protected]> napisał(a): > > >> > > > > >> > > wt., 9 paź 2018 o 13:45 Ard Biesheuvel <[email protected]> > > >> > napisał(a): > > >> > > > > > >> > > > On 9 October 2018 at 13:32, Marcin Wojtas <[email protected]> > > >> > > > wrote: > > >> > > > > wt., 9 paź 2018 o 13:28 Wu, Hao A <[email protected]> > > >> > > > > napisał(a): > > >> > > > >> > > >> > > > >> > -----Original Message----- > > >> > > > >> > From: edk2-devel [mailto:[email protected]] On > > >> > Behalf Of Ard > > >> > > > >> > Biesheuvel > > >> > > > >> > Sent: Monday, October 08, 2018 11:10 PM > > >> > > > >> > To: Marcin Wojtas; Ni, Ruiyu; Wu, Hao A > > >> > > > >> > Cc: Tian, Feng; Tomasz Michalec; Dong, Eric; edk2-devel-01; > > >> > > > >> > Gao, > > >> > Liming; > > >> > > > >> > Nadav Haklai; Kinney, Michael D; Zeng, Star > > >> > > > >> > Subject: Re: [edk2] [PATCH v2 2/4] MdeModulePkg/SdMmcPciHcDxe: > > >> > Add > > >> > > > >> > UhsSignaling to SdMmcOverride protocol > > >> > > > >> > > > >> > > > ... > > >> > > > >> > > > >> > > > >> > I suppose this is defined by the eMMC spec. > > >> > > > >> > > > >> > > > >> > Ruiyu, Hao, could you clarify? Are the host control 2 > > >> > > > >> > register values > > >> > > > >> > for HS200/HS400 defined by the eMMC spec? > > >> > > > >> > > >> > > > >> Hi Ard and Marcin, > > >> > > > >> > > >> > > > >> As far as I know, the EMMC Electrical Standard Spec 5.1 > > >> > > > >> (latest) does > > >> > not > > >> > > > >> mention on how to set the "UHS Mode Select" field of the Host > > >> > Control 2 > > >> > > > >> Register when switching to HS200/HS400. (Actually, the EMMC spec > > >> > does not > > >> > > > >> mention Host Control 2 Register at all) > > >> > > > >> > > >> > > > >> When it comes to setting the bus mode for EMMC devices, the > > >> > > > >> current > > >> > > > >> implementation of the SdMmcPciHcDxe driver does a mapping when > > >> > setting the > > >> > > > >> Host Control 2 Register: > > >> > > > >> > > >> > > > >> EMMC High Speed SDR - Freq: 0-52 MHz, Data Rate: Single > > >> > > > >> matches > > >> > > > >> SD SDR25 - Freq: 0-50 MHz, Data Rate: Single > > >> > > > >> > > >> > > > >> EMMC High Speed DDR - Freq: 0-52 MHz, Data Rate: Dual > > >> > > > >> matches > > >> > > > >> SD DDR50 - Freq: 0-50 MHz, Data Rate: Dual > > >> > > > >> > > >> > > > >> EMMC HS200 - Freq: 0-200 MHz, Data Rate: Single > > >> > > > >> matches > > >> > > > >> SD SDR104 - Freq: 0-208 MHz, Data Rate: Single > > >> > > > >> > > >> > > > >> EMMC HS400 - Freq: 0-200 MHz, Data Rate: Dual > > >> > > > >> matches > > >> > > > >> SD None > > >> > > > >> > > >> > > > >> And there is no obvious counterpart for the EMMC HS400 mode in > > >> > > > >> the > > >> > SD > > >> > > > >> spec. The driver currently sets the "UHS Mode Select" field to a > > >> > reserved > > >> > > > >> value 0x5. > > >> > > > >> > > >> > > > > > > >> > > > > Thank you Hao, above is on par with what the default UhsSignaling > > >> > > > > routine does in this patch. IMO especially in case the EMMC > > >> > > > > standard > > >> > > > > is not unequivocal regarding UHS_MODE_SEL, I'd encourage to > > >> > > > > accept > > >> > > > > some way of updating HostControl2 register, depending on the > > >> > > > > implementation. What is your opinion Ard? > > >> > > > > > > >> > > > > > >> > > > I would like to know where the current values in SdMmcPciHcDxe come > > >> > > > from if they are not defined in any spec. > > >> > > > > > >> > > > How do we know which ones are the correct ones? > > >> > > > > >> > > Hao, can you justify used values? > > >> > > > > >> > > > >> > Hi Hao, > > >> > > > >> > Can you please take a look at the UHS_MODE_SEL values source for eMMC? > > >> > > >> Hi Marcin, > > >> > > >> Sorry for the delayed response. > > >> > > >> For the current implementation of the SdMmcPciHcDxe driver, the selecting > > >> of "UHS Mode Select" field value of the Host Control 2 Register is based > > >> on a Max Clock Frequency & Data Rate (Single or Dual) matching > > >> relationship between the: > > >> > > >> A. Table 3-6 of the SD Specifications Part 1 Physical Layer Simplified > > >> Specification Version 4.10 > > >> > > >> and > > >> > > >> B. Table 4 of the EMMC Electrical Standard Spec 5.1 > > >> > > >> The matching details was included in my previous reply. The only missing > > >> part is there seems no matching for the EMMC HS400 mode in the SD > > >> specifications. For this case, we are currently using the same approach > > >> with the Linux implementation, that is to set the "UHS Mode Select" to a > > >> value of 0x5 (not standard). > > >> > > > > > > Hao, > > > > > > Thanks a lot for the clarification. > > > > > > Ard, > > > > > > Knowing the numbers details, what is your view of the UhsSignaling > > > handling? > > > > > > > I think it makes sense to be able to override the SD->MMC mapping for > > HC2 attributes. But it seems to me that this mapping is rather ad-hoc > > and so it should apply to all configuration that is inferred: > > UhsSignalling does not quite cover it. > > > > So I think the approach is correct, but we need a better name. > > Do you mean to update more fields in HC2 than UHS_MODE_SEL?
AIUI the EMMC spec does not mention HC2 at all, and yet we have to set it to a sane value, and we are currently using fuzzy logic for it. Or are the other fields less ambiguous? _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
